The present invention relates to a drive device for all wheel drive motor vehicles.
All-wheel drives for motor vehicles, in particular passenger cars, can be roughly divided into permanent drives with two axle differentials and an intermediate axle differential (for avoiding drive tensions) and so called hang-on drives with a primary axle that is directly driven by the drive aggregate and a secondary axle that can be activated in the case of drive slip via a clutch (for example a viscous clutch or a Haldex clutch). The primary axle or secondary axle can hereby be the front axle or the rear axle of the motor vehicle.
JP 2005 035 379 A1 discloses a drive device in which the drive of the secondary axle of the motor vehicle is accomplished via a toothed belt drive as transmission means from the primary axle to the secondary axle. The differentials of the two axles are arranged in a conventional manner coaxial to the drive shafts that output to the wheels. Further a controllable clutch is provided via which the force flux to the secondary axle can be interrupted for achieving for example only a front drive of the motor vehicle.
From WO 81/03150 a generic drive device is known in which a secondary axle is impinged, via two lateral belt drives, by the primary axle of the motor vehicle or drive shafts of the primary axle that output on the wheels. Via the single axle differential only on the primary axle, however, rotational speed differences of the wheels, in particular when negotiating curves, cannot be compensated satisfactorily.